A computer, which has multimedia features, includes a multimedia subsystem, a central processing unit, Input/Output circuits that allow the computer to receive and transmit data with other computers and computer peripherals, such as a computer monitor. The multimedia subsystem includes a video graphics circuit, an audio processing circuit, a television tuner, a television encoder, and a video capture circuit. The video graphics circuit, based on data received from the central processing unit, provides pixel information, in a red, green and blue ("RGB") format, to the computer monitor, which may be a CRT, and to the television encoder. The television encoder converts the RGB output into a composite TV signal (E.g. NTSG, PAL, SECAM) data which can be then displayed on a television set. In addition, the pixel information may be provided to an RGB capture circuit, which allows the computer to store video data in the digital domain.
The basic architecture of the multimedia subsystem has been in existence since the 1980's and has been modified only slightly since. The modifications include adding a common bus that couples the video graphics card, a video capture circuit, the television encoder, the television tuner, and the audio processing circuit together. Thus, the circuits of the newer multimedia subsystem architectures provide for greater data capabilities and to operate at much higher data rates than their predecessors.
To test the video output of a multimedia subsystem, a sensor is placed over the CRT, which is coupled to the video graphics circuit output, to determine the visual aspects of video data being displayed. The sensor monitors the video aspects of the CRT and, using an ICC profile table, determines the color spectrum of the images being displayed. While this technique works well to verify the functionality of the video graphics circuit, the cost of such sensors is in the range of $500.00 to $700.00, per sensor, which is cost prohibitive to include the sensor in consumer market personal computers that roughly costs in the range of $1,500.00 to $3,500.00.
To test the video capture circuit, and the TV encoder, the video capture circuit is provided with an input test pattern and the television encoder output is monitored using a vector scope. In essence, a human monitors the output on the vector scope to determine whether the video capture circuit and the television encoder are functioning properly.
To test the television tuner, it receives a video input from a video generator and converts the video input into a base video signal. (Note that a good quality video generator costs $3,000 to $5,000.) The base video signal is subsequently provided to the video capture circuit which converts the base signal into a digital signal that is subsequently provided to the television encoder. The television encoder converts the signal to produces a YUV output that is tested by human interaction using a vector scope. If the vector scope yields a pattern which conforms to an anticipated pattern, the television tuner, the video capture circuit, and the television encoder are determined to be functional. While this technique works well to verify the functionality of these circuits, a vector scope costs in excess of $10,000.00.
Therefore, a need exists for a method and apparatus for testing a multimedia subsystem that is not cost prohibitive for the consumer market.